Cranberry Juice May Improve Outcomes for UTIs Alongside Antibiotics: Study

A new in vitro study supported by The Cranberry Institute found that cranberry juice may help to enhance the activity of the antibiotic fosfomycin, which is used to treat urinary tract infections (UTIs) caused by E. coli. The findings were published in Applied and Environmental Biology.

According to the findings, cranberry juice may help to make E. coli strains in the urinary tract less resistant to Fosfomycin, and appear to make the bacteria more sensitive to the antibiotic.

“Spontaneous resistance frequently arises through mutations in bacterial transport systems,” the authors wrote. “Cranberry juice is known for its anti-adhesive and anti-infective properties; however, its potential to modulate antibiotic activity remains poorly understood. Here, we show that cranberry juice markedly potentiates the antibacterial activity of [Fosfomycin] and limits the emergence of resistance,” in in vitro isolates. In 72% of the isolates, cranberry juice increased the activity of the antibiotic and resistant mutations “by up to five orders of magnitude,” the authors wrote.

Fosfomycin is actively transported inside the bacteria cell via two uptake mechanisms, GlpT and Uhp-T, which are used by the bacteria to acquire nutrients. The main entry point for Fosfomycin is GlpT; however, when exposed to cranberry, bacteria appear to increase the function of the Uhp uptake system, bolstering the ability of Fosfomycin to clear the infection.

Meanwhile, the proanthocyanidins found in cranberries also interfere with E. coli bacteria’s ability to adhere to the wall of the urinary tract.

“The bioactive compounds in cranberries help prevent bacterial adhesion in multiple areas of the body, including not only the urinary tract but also the stomach and oral cavity,” said Amy Howell, PhD, who has researched cranberries for more than 30 years at Rutgers University. “Bacteria sticking to surfaces in the body is the first step in the infection process, so preventing this adhesion with cranberry intake can keep the infection from proceeding further.”